I agree she is arrogant. She is entitled, she is full of herself. However, i think this analysis is best: She was raised to have confidence and excellent self-esteem. That's great, her parents did a great job. Obviously she had the best of everything.
However, while that demeanor may work in the outside world, inside the house it is really obnoxious. I dislike her. I hope she does not win. She will become unbearable.